1. Field of the Invention
This invention relates to a light beam scanning apparatus, a light beam scanning read-out apparatus, and a light beam scanning recording apparatus. This invention particularly relates to a light beam scanning apparatus, a light beam scanning read-out apparatus, and a light beam scanning recording apparatus wherein light beam scanning is conducted by generating a surface acoustic wave in a wave guide and utilizing the coupling action of a grating generated by the surface acoustic wave with guided wave.
2. Description of the Prior Art
Light beam scanning type recording apparatuses and read-out apparatuses have heretofore been used widely. As the light beam scanning apparatuses for one-dimensionally scanning a recording light beam or a reading light beam in the recording apparatuses and the read-out apparatuses, those as described below are known. (1) Apparatuses wherein the light beam is deflected and scanned by a mechanical type light deflector such as a galvanometer mirror or a polygon mirror (multi-face rotating mirror). (2) Apparatuses wherein the light beam is deflected and scanned by a light deflector using solid-state light deflecting device, such as an EOD (electro-optic deflector) or an AOD (acousto-optic deflector). (3) Apparatuses wherein a shutter array such as a liquid crystal device array or a PLZT array is combined with a linear light source, the shutter devices of the shutter array are independently connected to drive circuits and turned on and off in accordance with an image signal to conduct linear sequential scanning. (4) Apparatuses wherein many light emitting devices such as LEDs are arrayed in a line, independently connected to drive circuits, and turned on and off in accordance with an image signal to conduct linear sequential scanning.
The light beam scanning apparatuses described in (1) have the drawbacks that the mechanical type light deflector is weak against vibration, exhibits low mechanical durability, and requires troublesome adjustments. Further, a large optical system is necessary for swinging and deflecting the light beam, and the recording apparatuses and the read-out apparatuses become large.
The light beam scanning apparatuses described in (2) and using the EOD or AOD have the same drawback that the apparatuses become large to swing and deflect the light beam. Particularly, since the light deflection angle cannot be adjusted large with the EOD and AOD, the optical system becomes larger than in the case where the mechanical light deflector is used as described in (1).
In the light beam scanning apparatuses using the shutter array as described in (3), since two polarizing plates must be used, the light utilization efficiency of the light source is very low.
The light beam scanning apparatuses using many light emitting devices arrayed in a line as described in (4) have the drawback that, since fluctuations arise in light emission intensity between the light emitting devices, the apparatuses are not suitable for accurate scanning.